Research On Power Generation System Using Low-temperature Organic Rankine Cycle

Now the world energy situation is tense,The new generation technology combining lowtemperature energy with organic Rankine cycle has the advantages of simple structure,low cost and environmental protection,the development prospect is very broad.This paper studies the organic Rankine cycle power generation system based on low-temperature energy,which is of great significance to optimize the energy structure.Firstly,analyzed the principle of organic Rankine cycle theoretically,selected seven dry working fluids as research objects of this paper with the principle of classification and selection.Analyzed influences of evaporation temperature,condensation temperature,superheat degree and inlet pressure on thermal efficiency,net work output,total irreversible loss and exergy efficiency,obtained the best working fluid and the influence law of operating parameters on system performance.Secondly,designed the centripetal expander suitable for the organic Rankine cycle system and establish its model.Analyzed its working principle and selected the variable parameters based on the wheel cycle efficiency,carried out expander’s pneumatic design and obtained main thermal and structural parameters,built the three-dimensional models of guide blade and rotor blade with BladeGen.Then simulated and analyzed the flow field inside the centripetal expander.Selected the turbulent flow model based on the governing equation and meshed guide blade and rotor blade,in order to improve the accuracy of simulation,the local grid was encrypted to ensure that the first layer is at the viscous bottom layer.Set the boundary conditions and solver,and the flow field characteristics of the expander were simulated by Ansys CFX,the results show the expander performance meets the design requirements,guide blade’s flow field is smooth,the pressure and velocity change uniformly,rotor blade’s flow field is relatively complex and there is a certain flow loss.In order to improve the performance of the expander,analyzed the influences of blade outlet height,meridional flow channel width,inlet pressure and inlet temperature on the performance of the expander.Finally,designed the 75 kW ORC power generation system,constructed its overall scheme and then designed its circulation flow including heating system part,working medium circulation part,cooling part and pressure reduction part.Calculated the main parameters in the operation of the power generation system,and the selections of main equipments of the power generation system is completed based on the calculation results.